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Low altitude mixture cuts in twin training still occuring despite CASA warnings

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Low altitude mixture cuts in twin training still occuring despite CASA warnings

Old 22nd Feb 2012, 13:03
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I have yet to fly a GA piston twin which had any serious chance of suffering from increased power on any engine - even more so during the take-off sequence.
What would happen in a turbocharged light twin if the waste-gate controller failed to the closed position.

Overboost with a yaw away from the "failed" (overboosted) engine?
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Old 23rd Feb 2012, 11:56
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Similar event to a wastegate failing open. If you retard the throttle and the noise changes (similar to misidentifying a failed engine), leave it alone. MP check will show up the issue VERY quickly and corrective action can be taken. If it is a failed open scenario, any thrust is better than a feathered engine. A wastegate failing open will still produce around 75% power at sea level in a PA-31.

Overboost is simply controlled by reducing throttle. With the Diff Pressure and Dens. Alt. controllers on a 31, they allow oil to bleed out of the system to open the wastegate. Excessively cold oil can produce an overboost (too thick and unable to leave the system). Even experienced it once, control change nowhere near the degree of a severe power loss failure, though.
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Old 23rd Feb 2012, 21:40
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Read this and it took just 22.5 seconds from V2

The Brasilia in Darwin [EFATO]:

http://www.atsb.gov.au/media/3546615/ao-2010-019.pdf
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Old 25th May 2012, 13:12
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Mixture cuts on take off at Moorabbin

A student recently completed an initial multi-engine endorsement at a Moorabbin flying school. The grade one instructor simulated engine failure after take-off on several occasions by cutting the mixture control, rather than closing the throttle.

Some years ago, CASA produced a CAAP after several fatal accidents involving simulated engine failures using the mixture control? The following extract from CAAP 5.23-1 amplifies this by stating:

“Do not simulate an engine failure using procedures that may jeopardise the restoration of power. It would be folly to simulate an engine failure at low level by selecting the mixture to idle cut-off or turning the fuel selector off. These procedures would be more appropriate at higher altitude”.

The above case involves just one senior one instructor at Moorabbin. But it makes one wonder how many other instructors deliberately disregard the sensible advice published in the CASA CAAP? In addition, if CASA is aware of this continued practice, why hasn’t it taken appropriate non-compliance action?

Surely the risks involved with mixture cuts after take-off, as well as the safety message published in the applicable CAAP, should be emphasised during the CASA approved multi-engine instructors’ course. On the other hand, there are doubtless some instructors who, in their over-confidence in their own abilities, refuse to change their ways in this regard. Maybe CASA needs to get its collective fingers out and fix the problem before another accident like the fatal Duchess accident at Camden occurs.
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Old 25th May 2012, 19:39
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Turning off the fuel would be foolhardy ...

but there IS NO SAFETY DIFFERENCE in simulating engine failure by pulling the mixture to idle cut-off, compared to pulling the throttle to idle.

Last edited by Checkboard; 25th May 2012 at 19:40.
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Old 25th May 2012, 21:22
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http://www.pprune.org/dg-p-general-a...-warnings.html

A37575, you started the above thread as well which provided robust discussion. Why start another thread unless you've got an axe to grind with said senior instructor...
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Old 25th May 2012, 21:28
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Turning off the fuel would be......stupid

Turning theMixture to Idle Cut Off would be ......foolhardy

Pulling the Throttle to zero thrust would be........good airmanship

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Old 25th May 2012, 21:54
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It's pretty scary... every time I loop a C152, or a Chipmunk, or a Citabria, the engine stops.

I had no idea that I was in such danger.
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Old 25th May 2012, 21:54
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There is no mandated requirement on mixture or throttle.

So it is basically a preference thing.

Pulling the mixture on a piston for EFATO training will not make the wings fall off.

It is far more realistic than a throttle cut, throttle cuts will not give you the assymetric yaw required to properly demonstrate what you would see in an actual engine failure.

I personally would not shut down a turbine whilst conducting EFATO training with the condition lever / Stop and feather or fire wall shut off.

Some believe a throttle cut may be safer ( I do not agree, if you mess up either and VMCA into the ground its the same outcome, watch the airspeed and adjust as required, restart the other engine if the fecal matter is going to hit the fan ).

if CASA is aware of this continued practice, why hasn’t it taken appropriate non-compliance action?
Which piece of legislation would you suggest these instructors are in breach of ? ( noting : CAAPS are not legislated ).

I have been tested by the CASA FOI's many times, to the best of my recollection, every time they used the mixture.

Emeritus, what makes you so certain of what is and is not good airmanship ?, re-inventing the wheel are we ?.

Last edited by Josh Cox; 25th May 2012 at 22:54.
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Old 26th May 2012, 00:00
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Probably a higher risk of carby icing from taking the engine to idle than a mixture cut. In both situations the rpm is about the same, so the engines are pumping about the same amount of air ao the same temperature. For the minute or so that the engine is shut down the residual heat of the engine probably means the engine temps are pretty similar. But, at idle you still have the effect of evaporative cooling from the fuel spray in the carburetor cooling the carburetor venturi which doesn't exist if the mixture is cut.

Maybe there is an argument that mixture cuts are safer after all?
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Old 26th May 2012, 01:00
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Old Akro,

I have never conducted multi engine training on an aircraft with a Carby engine, but what you've spoken of is a very real threat in my mind.

With the training I've conducted, unless you feather the prop, the prop is still rotating due to the airflow, if the engine is needed at short notice, which does happen on occasion ( that's why its called training ): take over, lower the nose, mixture rich and the engine fires back to life instantly.

I will never never never feather a prop when conducting EFATO training, as soon as the pilot in the LH seat correctly identifies the failure, I will set the mixture to rich ( or there abouts ) and set zero thrust ( circa 12-14 inches ).

I would also never feather a turbine, zero thrust also. With condition lever at high idle the prop will still take +10 seconds come out of feather and start producing TQ ( clearly does not apply to Garretts ).

Restarting a piston engine with a prop in feather is a PITA and does not always restart.

Most legislation finds it's genesis in the many and varied accidents the industry experiences.

Last edited by Josh Cox; 26th May 2012 at 01:08.
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Old 26th May 2012, 01:07
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Probably a higher risk of carby icing from taking the engine to idle than a mixture cut
I doubt if carb ice would form to a significant degree in the less than 15 seconds it takes to close the throttle to simulate engine failure, have the student identify which engine has `failed` and for the instructor to then add a little power on that engine to simulate zero thrust (nominally around 12inches of manifold pressure).

Following the Air North Brasilia fatal crash at Darwin where the check pilot pulled back the throttle to simulate engine failure shortly after lift off, CASA mandated that all future emergency training in certain types of aircraft (practice engine failure on take off), must be conducted in an approved flight simulator. This mandate recognised the risks involved with any deliberate low altitude engine failure practice.

The history of these type of accidents due to mis-handling of practice engine failures in multi-engine aircraft, goes back many decades. Indeed, a fatal crash at Camden in a de Havilland Dove in the 1950's was caused by the then common practice of not only pulling the mixture but actually feathering the prop. A senior DCA Examiner of Airman was killed in that crash while the instructor lost an eye. Clearly the instructor took the chance that everything would work out OK and tragically it didn't.

Let's not be coy about all this. Pulling the mixture fails the engine dead and the prop immediately windmills creating drag that will prevent a positive rate of climb. That is why the feathering propeller was designed in the first place. So the instructor has created an immediate serious emergency when there was nothing wrong with the engine in the first place.

If the instructor is so enthusiastic as to create a real emergency shortly after lift off in order to show off to his student how realistic the situation has become, maybe he should spare the time one day to speak to the relatives of those who have lost their lives in the push for realism. I doubt if he would receive much admiration from them for his actions.

Of course asymmetric training is a requirement; but I would have thought that common sense (good airmanship) would dictate caution when dicking around with practice engine failures near the ground, where the room for error is small. There will always be macho personalities among certain types of instructors who, in their misguided and even reckless enthusiasm, will risk the lives of their students in order to demonstrate realism. Wiser heads will have learned from the lessons of the past and realise there is a limit to realism, beyond which is sheer idiocy. Some may argue mixture cuts at low level fall into the latter category.

Last edited by A37575; 26th May 2012 at 01:15.
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Old 26th May 2012, 01:26
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Let's not be coy about all this. Pulling the mixture fails the engine dead and the prop immediately windmills creating drag that will prevent a positive rate of climb. That is why the feathering propeller was designed in the first place. place. So the instructor has created an immediate serious emergency when there was nothing wrong with the engine in the first place.
I disagree, the situation is a very real and scary situation you could find yourself in the middle of, having some quality hands on training is valuable for actually dealing with the situation in real life.

Sure, its entails a greater level of risk than flying around on two engines, but when the instructor is both well trained and experienced, the risk can be greatly reduced.

A multi engine aircraft with EFATO, using the correct technique, is capable of climbing.

Its the application of the correct procedures, drills and technique that allows the aircraft to fly away from the ground, not whether the instructor retards the throttle or mixture.

Of course asymmetric training is a requirement; but I would have thought that common sense (good airmanship) would dictate caution when dicking around with practice engine failures near the ground, where the room for error is small. There will always be macho personalities among certain types of instructors who, in their misguided and even reckless enthusiasm, will risk the lives of their students in order to demonstrate realism. Wiser heads will have learned from the lessons of the past and realise there is a limit to realism, beyond which is sheer idiocy. Some may argue mixture cuts at low level fall into the latter category.
A37575, do you have a personal agenda ?, sounds to me like you dislike this instructor and are not willing to vary from this mindset.

Last edited by Josh Cox; 26th May 2012 at 01:31.
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Old 26th May 2012, 01:39
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casa and EFATO

What is the AFM?? and what does it say:

The real issue here is what the Aircraft Flight Manual [AFM] says - which is the only legal way the aircraft can be operated.

In the case that I have used, which is relevant to the PA-30 "caused prang" at Camden.

The flight manual is as below and it says that simulated engine failure should be performed at an altitude that will allow for enough room for safe recovery (5000FT min. terrain clearance is recommended) should control of the aircraft be lost.

The AFM for a PA30-160 [A,B and C] is below.:



We must read and obey the AFM.

It is there for our safety, otherwise we are entering the world of a "test pilot".

Last edited by Up-into-the-air; 26th May 2012 at 01:59.
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Old 26th May 2012, 01:53
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A multi engine aircraft with EFATO, using the correct technique, is capable of climbing.
Josh Cox,
With all due respect, that statement is simply not true for a FAR 23 piston twin.

Under some circumstances, it will, or maybe not, excepting aircraft certified to the "Commuter amendment", it's all in the AFM for the aircraft.

Unless somebody wants to correct me ( I wouldn't want to make the heinous and earth shattering mistake of confusing the first names of my two friends "Butson" again) I don't know of a type of twin commonly used for initial twin training in Australia, which is certified to continue after an engine failure on takeoff.

I would also read CAR 138 carefully ---then read the AFM for whatever you are flying --- if you live after the bingle, CASA may not be your greatest problem ---- it could very well be the insurance company/aircraft owner.

Frankly, I would have thought that the steadily rising death toll from practices that should have been abandoned years ago, was argument enough.

Tootle pip!!

PS: Polar Air --- I would prefer to believe the description of C.Butson, Esq. as to the genesis of the audit that proved so disastrous for Polar Air, than alternative histories. But, hey, it's a free world, you can believe in Chemtrails, if you are so disposed.
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Old 26th May 2012, 01:58
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A37575, let it go, you're like an OC dog who won't stop chasing that tennis ball...

You're confusing many things bringing the Air North crash into it yet debating mixture cuts at the same time. Who gives a flying f$&@ whether you use the mixture or throttle in a piston - the killer, literally, it the circumstances whe the simulated failure occurs. Mishandling at low level or slow airspeed kills people, not the fact the mixture was used. Guess what, in every light twin I simulated engine failures in, riching the mixture would instantly provide power. Not saying this will happen for every twin in the world, but I did the research and it worked for the light twins I flew - which probably make up 90% of the twin training market.

Go up in your typical twin trainer and experiment mixture vs throttle and the rubbish you're talking about windmilling. The prop will 'windmill' no matter the technique until a zero thrust setting is used. The mixture has to be richened for this setting even if the idle cut was originally used.

Go back and re-read the informed posts on the previous pages which explain why pulling the mixture isnt 'shutting down' the engine.

Then go have a beer, chill out and worry about yourself instead of trying to change everyone. If you want to stick to throttle cuts, go for it, but don't crucify those who use mixture cuts after considering the engine, aircraft type and how they'll set zero thrust as per the AFM. And if CASA's FOIs all have different opinions about 'how' to simulate the failure, what chance do us mere mortals have?

The topic that should be debated is 'low level simulated engine failures' In general - leave the initial failure technique out of it.
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Old 26th May 2012, 02:20
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Captain Sled,

Under some circumstances, it will, or maybe not
No argument from me.

I was not referring to certification status of said aircraft, generally speaking, two pilots onboard, two hours fuel, capital city airport, ISA + 10 with ten knots of head wind, the "general training environment", most, if not all aircraft will have some form of positive performance when correctly flown, which as a part of the training environment offers some really good lessons to the trainee pilot. ( poorly described by me, but that was my general concept )

A C402B, with fours hours fuel, 6 POB at YBMA on a 42 degree day, from my experience, does not climb...........................

Up-in-the-air:

The word "recommended" and "should" does not mandate a requirement ( different to "must").

The words: can, should, must, recommended, prohibited etc etc all have very different meanings.

Try reading the Jepps, looking very closely at these words. It changes to meaning of many things quite considerably.

Last edited by Josh Cox; 26th May 2012 at 02:26.
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Old 26th May 2012, 03:27
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A good read this thread, for anybody who flies twins!

From a students point of view however, I've never had any problem with having the mixture cut on simulated EFATO. I've never felt unsafe, but of course I've never experienced a problem restarting the engine when the instructor is setting simulated feather. I personally don't see it as a big issue, as there's certainly a multitude of other problems that COULD happen, unrelated to the engine, that would stop the aircraft from climbing/maintaing height.

Does having the mixture cut as opposed to closing the throttle have any affect as to how the student would see and respond to a real life scenario? In my scenarios, the instructor has always used his other hand to shelter my eyes from the mixture, leaving it up to me to decipher which engine has failed as per instruments, visual clues or whatever it may be. Additionally, I personally felt a slight urgency to learn and conduct my checks accurately with the mixture cut as opposed to being able to immediately apply climb power if I stuffed anything up.

Last edited by seneca208; 26th May 2012 at 03:28.
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Old 26th May 2012, 07:04
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Additionally, I personally felt a slight urgency to learn and conduct my
checks accurately with the mixture cut as opposed to being able to immediately apply climb power if I stuffed anything up.
In your typical light twin i.e. PN68, Duchess, Seneca etc., by increasing the mixture back to rich you will have full power available again within about 1 second. Never had any hiccups using this technique in over 1000 hours of piston multi-engine training.
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Old 26th May 2012, 09:03
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In your typical light twin i.e. PN68, Duchess, Seneca etc., by increasing the mixture back to rich you will have full power available again within about 1 second. Never had any hiccups using this technique in over 1000 hours of piston multi-engine training.
Ah, I completed my initial multi training in a Seneca. Makes sense.
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